Atherosclerosis is a leading cause of death in the Western world, and hypercholesterolemia is a well-known risk factor for its development. Vasomotor abnormalities, in part due to hypercholesterolemia, are present prior to the onset of overt atherosclerosis and might play a role in disease progression. The role of nitric oxide (NO) and superoxide anion in cholesterol-induced vasomotor dysfunction and atherosclerosis is unclear. NO is generated in the endothelium by eNOS and can be inactivated with superoxide anions. Superoxide anions are scavenged by SOD. This project was designed to determine the role of NO and superoxide in cholesterol-induced vasomotor dysfunction by overexpressing the genes for eNOS, CuZnSOD and MnSOD in hypercholesterolemic rabbits. This project is designed to determine the role of endothelial nitric oxide synthase (eNOS) and superoxide dismutase (SOD) in cholesterol-induced vasomotor dysfunction by overexpressing the genes for endothelial eNOS, copper zinc superoxide dismutase (CuZnSOD)and manganese superoxide dismutase (MnSOD) in the hypercholesterolemic rabbit carotid artery. The long term goal of this research is to examine the role of NO and superoxide anion in atherogenesis. eNOS and SOD overexpression (both isoforms) in the arterial wall of rabbits will be achieved in vivo using gene transfer with adenoviral vectors. Cholesterol-induced vasomotor dysfunction will be compared in animals treated with vectors expressing eNOS and/or SOD and controls. Results from these studies should provide fundamental information about the roles of NO and superoxide anions in cholesterol-induced vasomotor dysfunction, and the data might provide useful information for the development of gene therapy-based strategies for the treatment of this disorder. The long-term goal of this research is to examine the role of NO and SOD in atherogenesis. eNOS and SOD overexpression in arteries will be done in vivo using a gene transfer technology that employs adenoviral vectors. Cholesterol-induced vasomotor dysfunction will be compared in animals treated with vectors expressing eNOS and/or SOD and controls. Specific Aim 1 is to determine the role of eNOS in cholesterol-induced vasomotor dysfunction. It is hypothesized that NOS activity and cGMP levels are reduced in atherosclerotic-induced vasomotor dysfunction and that restoration of eNOS activity and cGMP levels improves vasomotor responses. Specific Aim 2 is to determine if SOD is an important regulator of vasomotor tone. It is hypothesized that adenoviral vectors of SOD attenuate cholesterol-induced vasomotor dysfunction, and that CuMnSOD is the most active of the two SOD isoforms. Specific Aim 3 is to determine the relative roles of eNOS and SOD in cholesterol-induced vasomotor dysfunction. It is hypothesized that co-expression of SOD with eNOS will augment vascular relaxation.